Engineering of Battery Type Electrodes for High Performance Lithium Ion Hybrid Supercapacitors

The prospect of supercapacitors in integrated energy harvesting and storage systems

Renewable energy sources, such as wind, tide, solar cells, etc, are the primary research areas that deliver enormous amounts of energy for our daily usage and minimize the dependency upon fossil fuel. Paralley, harnessing ambient energy from our surroundings must be prioritized for small powered systems. Nanogenerators, which use waste energy to generate electricity, are based on such concepts. We refer to these nanogenerators as energy harvesters. The purpose of energy harvesters is not to outcompete traditional renewable energy sources. It aims to reduce reliance on primary energy sources and enhance decentralized energy production. Energy storage is another area that needs to be explored for quickly storing the generated energy. Supercapacitor is a familiar device with a unique quick charging and discharging feature. Encouraging advancements in energy storage and harvesting technologies directly supports the efficient and comprehensive use of sustainable energy. Yet, self-optimization from independent energy harvesting and storage devices is challenging to overcome. It includes instability, insufficient energy output, and reliance on an external power source, preventing their direct application and future development. Coincidentally, integrating energy harvesters and storage devices can address these challenges, which demand their inherent action. This review intends to offer a complete overview of supercapacitor-based integrated energy harvester and storage systems and identify opportunities and directions for future research in this subject.

Carboxymethyl cellulose mediated growth of V2O5 nanorod by green strategy for energy storage utilization using electrochemical studies

Vanadium pentoxide has the most exciting oxidation states, but, Vanadium pentoxide (V₂O₅) has low capacitance due to poor electrical conductivity and ionic diffusivity. So, encapsulating pentoxide in carbonaceous materials or metals, shrinking it to the nanoscale, or changing its morphology can improve capacitance performance. Herein, we describe a green synthesis of V₂O₅NPs with carboxymethyl cellulose (CMC) that typically acts as a reducing and stabilizing agent using the -COOH and -OH group. The physicochemical characterization of prepared samples reveals the prominent peak in UV-vis spectra at 265 nm confirming the formation of V₂O₅NPs with particle sizes between 200 and 220 nm. The theoretical surface area for the nanocomposite was 76.5 m²/g. The calcination temperature is essential to determine a material's specific capacitance. Due to decreased oxide agglomeration, the V₂O₅-green modified electrode exhibits superior electrochemical performance around 223 F g^-1 than Ac alone (160 F g^-1). The finding demonstrated excellent cyclic stability with reduced fluctuation in capacitance. Because of its exceptional electrochemical performance and simplicity of access, this AC/V₂O₅ nanocomposite can be helpful as an electrode for energy storage applications.